Generally, waterproof air-permeability is achieved by passing gases, such as water vapor, and not passing liquids. In order to produce such a waterproof air-permeable living article, a flat waterproof air-permeable membrane is used. The waterproof air-permeable membrane is a membrane that passes gases such as air and water vapor but does not pass liquids such as water, and used as various kinds of uses such as a disposable diapers and disposable sanitary pad covers, disposable clothing or waterproof clothing such as sportswear or anti-epidemic clothing, architectural house wraps, packaging materials, or sanitary materials.
Recently, various attempts have been made to develop a component having more excellent waterproof air-permeability in order to maintain the reliability of components optimally in various fields such as electronic devices, automobiles, and aviation.
For example, since portable electronic devices are carried and used, a waterproof function is required. At the same time, portable electronic devices are provided with sound-transmitting holes for emitting sound from a speaker or a microphone to the outside or for passing sound from the outside to the inside. Water or dust may penetrate into the electronic device through the sound-transmitting hole, and thus a waterproof filter or a waterproof sound sheet for passing sound and blocking water and dust should be installed in the sound-transmitting hole.
Korean Patent Application Publication No. 10-2011-0030582 (Patent Document 1) discloses an acoustic component in which a waterproof filter is made of porous polytetrafluoroethylene as a fluorine resin, and is attached to an outer case of an electronic device to cover the sound-transmitting hole by using a double-sided adhesive tape.
In the above-described Patent Document 1, a double-sided adhesive tape is used to attach the waterproof filter to the case. Since the double-sided adhesive tape has a structure in which an adhesive layer is formed on either surface of a base layer, burs of an adhesive material occur from the adhesive layer at the time of blanking the double-sided adhesive tape in an annular form. In addition, if pressure is applied during a bonding process, the adhesive material of the adhesive layer cannot be absorbed into the base layer, but is released to the outside and leaked to the waterproof filter or the waterproof sound sheet. If the adhesive material of the double-sided tape leaks to the waterproof filter or the waterproof sound sheet, the sound transmission efficiency or sound transmission characteristics of the waterproof filter or the waterproof sound sheet are adversely affected.